Artificial intervertebral disc

ABSTRACT

The present invention is directed to the field of prosthetic devices. More particularly, one embodiment of the present invention is directed to an artificial disc that can be used as a replacement for an intervertebral disc (e.g., a human intervertebral lumbar disc, a human intervertebral cervical disc and/or a human intervertebral thoracic disc).

RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application Ser.No. 60/719,424, filed Sep. 22, 2005, U.S. Provisional Application Ser.No. 60/759,944, filed Jan. 18, 2006, U.S. Provisional Application Ser.No. 60/772,812, filed Feb. 13, 2006 and U.S. Provisional ApplicationSer. No. 60/745,303, filed Apr. 21, 2006. Each of the aforementionedapplications is incorporated herein by reference in its entirety.

FIELD OF THE INVENTION

The present invention is directed to the field of prosthetic devices.More particularly, one embodiment of the present invention is directedto an artificial disc that can be used as a replacement for anintervertebral disc (e.g., a human intervertebral lumbar disc, a humanintervertebral cervical disc and/or a human intervertebral thoracicdisc).

For the purposes of the present application the term “column” isintended to refer to a solid, partially hollow or hollow structurehaving any desired aspect ratio and any desired cross-section(cross-sectional shape and/or cross-sectional area). In one example(which example is intended to be illustrative and not restrictive) sucha column may have a high length to width aspect ratio (i.e., the columnmay be “elongated”). In another example (which example is intended to beillustrative and not restrictive) such a column may have a low length towidth aspect ratio (i.e., the column may be “squat”). In another example(which example is intended to be illustrative and not restrictive) thewalls of the column may be thick enough to provide a substantial degreeof inflexibility to the column. In another example (which example isintended to be illustrative and not restrictive) the walls of the columnmay be thin enough to provide a substantial degree of flexibility to thecolumn. In other examples (which examples are intended to beillustrative and not restrictive) such a column may have a cross-sectionwhich is circular, oval, square or “kidney-shaped”.

Further, for the purposes of the present application the term “filler”(e.g., as in column filler) is intended to refer to a substance disposedwithin a space or void which partially or fully fills the volume of thespace or void.

Further still, for the purposes of the present application the term“composite structure” is intended to refer to a hollow or partiallyhollow column including a filler disposed therein.

Further still, for the purposes of the present application the term“elastomer” is intended to include (but not be limited to): a silicone,a urethane, a PCV, a thermoplastic elastomer, an elastomer alloy; apolyurethane/polycarbonate alloy, and/or any combination thereof.

Further still, for the purposes of the present application the term“biologically acceptable metal” is intended to include (but not belimited to): Ti, cobalt chromium, surgical steel and/or any combinationthereof.

BACKGROUND OF THE INVENTION

As an alternative to spinal fusion techniques, numerous attempts havebeen made to design an artificial disc to replace, for example, anintervertebral lumbar disc that has become damaged or otherwiseunhealthy.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an exploded view of an artificial intervertebral discaccording to an embodiment of the present invention;

FIGS. 2A-2D show example assembly steps associated with the artificialintervertebral disc of FIG. 1;

FIG. 3 shows a cut-away view of the assembled artificial intervertebraldisc of FIG. 1;

FIG. 4 shows an exploded view of an artificial intervertebral discaccording to another embodiment of the present invention;

FIGS. 5A-5D show example assembly steps associated with the artificialintervertebral disc of FIG. 4;

FIG. 6 shows a cut-away view of the assembled artificial intervertebraldisc of FIG. 4;

FIGS. 7A-7F show example initial fixation mechanisms associated withartificial intervertebral discs according to the present invention;

FIG. 8 shows a cut-away view of an artificial intervertebral discaccording to another embodiment of the present invention;

FIG. 9 shows an exploded view of an artificial intervertebral discaccording to another embodiment of the present invention;

FIG. 10 shows a perspective view of the artificial intervertebral discof FIG. 9;

FIG. 11 shows a side view of the artificial intervertebral disc of FIG.9;

FIG. 12 shows a top view of the artificial intervertebral disc of FIG.9;

FIGS. 13A-13F show additional details of the artificial intervertebraldisc of FIG. 9 (FIG. 13A is a top view, FIG. 13B is a bottom view, FIG.13C is a side view, FIG. 13D is a side view, FIG. 13E is a side cut-awayview (along section B-B of FIG. 13A) and FIG. 13F is a detail view ofportion “C” of FIG. 13E);

FIGS. 14A-14D show additional details of a column and crimp rings of theartificial intervertebral disc of FIG. 9 (FIG. 14A is an exploded view,FIG. 14B is a top view, FIG. 14C is a side cut-away view (along sectionA-A of FIG. 14B) and FIG. 14D is a detail view of a portion of FIG.14C);

FIGS. 15A-15C show additional details of an inner crimp ring of theartificial intervertebral disc of FIG. 9 (FIG. 15A is a perspectiveview, FIG. 15B is a top view and FIG. 15C is a side cut-away view (alongsection A-A of FIG. 15B));

FIGS. 16A-16C show additional details of an outer crimp ring of theartificial intervertebral disc of FIG. 9 (FIG. 16A is a perspectiveview, FIG. 16B is a top view and FIG. 16C is a side cut-away view (alongsection A-A of FIG. 1613));

FIGS. 17A and 17B show additional details of a column of the artificialintervertebral disc of FIG. 9 (FIG. 17A is a top view and FIG. 17B is aside view);

FIGS. 18A and 18B show additional details of a column filler of theartificial intervertebral disc of FIG. 9 (FIG. 18A is a perspective viewand FIG. 18B is a side view);

FIGS. 19A-19I show additional details of an upper (i.e., caphalad)anchor plate of the artificial intervertebral disc of FIG. 9;

FIGS. 20A-20I show additional details of a lower (i.e., caudal) anchorplate of the artificial intervertebral disc of FIG. 9;

FIG. 21 shows a perspective view of an artificial intervertebral discaccording to another embodiment of the present invention;

FIGS. 22A-22N show diagrams of a surgical technique associated with thepresent invention;

FIG. 23A shows a side view of an artificial intervertebral discaccording to another embodiment of the present invention;

FIG. 23B shows a cross-sectional view of the artificial intervertebraldisc of FIG. 23A (taken along line B-B of FIG. 23A);

FIG. 24 shows an exploded view of an artificial intervertebral discaccording to another embodiment of the present invention;

FIG. 25 shows a perspective view of the artificial intervertebral discof FIG. 24;

FIG. 26 shows a side view of the artificial intervertebral disc of FIG.24;

FIG. 27 shows a top view of the artificial intervertebral disc of FIG.24;

FIGS. 28-33 show additional views of components of an artificialintervertebral disc according to another embodiment of the presentinvention; and

FIGS. 34-43 show additional views of components of an artificialintervertebral disc according to another embodiment of the presentinvention.

Among those benefits and improvements that have been disclosed, otherobjects and advantages of this invention will become apparent from thefollowing description taken in conjunction with the accompanyingfigures. The figures constitute a part of this specification and includeillustrative embodiments of the present invention and illustrate variousobjects and features thereof.

DETAILED DESCRIPTION OF THE INVENTION

Detailed embodiments of the present invention are disclosed herein;however, it is to be understood that the disclosed embodiments aremerely illustrative of the invention that may be embodied in variousforms. In addition, each of the examples given in connection with thevarious embodiments of the invention is intended to be illustrative, andnot restrictive. Further, the figures are not necessarily to scale, somefeatures may be exaggerated to show details of particular components.Therefore, specific structural and functional details disclosed hereinare not to be interpreted as limiting, but merely as a representativebasis for teaching one skilled in the art to variously employ thepresent invention.

One embodiment of the present invention provides an artificialintervertebral disc (“AID”) assembly comprised of first and secondanchor plates (each of which has a vertebrae contacting side) and atleast one composite structure that is fixed to the first and secondanchor plates. The composite structure may be comprised of a columnincluding woven and/or non-woven fiber(s). In one example (which exampleis intended to be illustrative and not restrictive), the column maycomprise polyester. In a more specific example (which example isintended to be illustrative and not restrictive), the column maycomprise DACRON. The column may be at least partially hollow (e.g.,having one or more holes therein) and may be filled (fully or partially)with a compressible material, such as an elastomer. For example (whichexample is intended to be illustrative and not restrictive), theelastomer may include a silicone, a urethane, a thermoplastic elastomer,an elastomer alloy; a polyurethane/polycarbonate alloy, and/or anycombination thereof.

Of note, the column filler (e.g., elastomer) may store energy and thenreturn the stored energy back to the physiological system (because thecolumn filler may allow physiological-like displacement, the columnfiller may (like a physiological system) dissipate some strain energy).

In one example (which example is intended to be illustrative and notrestrictive), the compressive properties of the artificialintervertebral disc may be tuned to largely match those found in anatural intervertebral disc by utilizing a generally parabolic function.In a specific example applicable to a cervical disc (when deflection isplotted on the x-axis and compressive load is plotted on the y-axis),the parabola generally may be described by the function y=A x²+B x+C,where the coefficient A is in the range of 700 to 2000, the coefficientB is in the range of 0 to 1500, and the coefficient C is in the range 0to 100 (the increasing stiffness is indicated by the increasing slope ofthe load-deflection curve at higher loads and deflections).

Referring now to FIG. 1 (showing one embodiment of the presentinvention), it is seen that Artificial Intervertebral Disc 100 includesFirst Anchor Plate 102A and Second Anchor Plate 102B (each Anchor Plate102A, 102B may comprise, for example (which example is intended to beillustrative and not restrictive), any desired biologically acceptablemetal). Of note, each Anchor Plate 102A, 10213 may have an outer surfaceconfigured to be disposed adjacent a respective vertebral endplate (notshown). Further, Core 104 (e.g., comprising an elastomer) is sandwichedbetween an inner surface of Anchor Plate 102A and an inner surface ofAnchor Plate 102B (in one example (which example is intended to beillustrative and not restrictive), the inner surfaces of Anchor Plates102A, 102B may be convex and may be received in respective concavitiesin Core 104). In addition, Cable 106 (e.g., comprising a polymer and/ora metallic material (e.g., including a biologically acceptable metal))is attached at a first end to Anchor Plate 102A and at a second end toAnchor Plate 102B (wherein Cable 106 runs from Anchor Plate 102A toAnchor Plate 102B through a hole disposed in Core 104).

In one example (which example is intended to be illustrative and notrestrictive), Cable 106 may be attached to Anchor Plate 102A at adepression formed in an inner surface of Anchor Plate 102A and Cable 106may be attached to Anchor Plate 102B at a depression formed in an innersurface of Anchor Plate 102B. In another example (which example isintended to be illustrative and not restrictive), Cable 106 may beattached to Anchor Plate 102A via a hole formed all the way throughAnchor Plate 102A (i.e., a hole extending from an inner surface ofAnchor Plate 102A to an outer surface of Anchor Plate 102A) and Cable106 may be attached to Anchor Plate 102B via a hole formed all the waythrough Anchor Plate 102B (i.e., a hole extending from an inner surfaceof Anchor Plate 102B to an outer surface of Anchor Plate 102B). Inanother example (which example is intended to be illustrative and notrestrictive), Cable 106 may be attached to Anchor Plates 102A, 102Busing any appropriate attachment mechanism (e.g., adhesive, welding,screw(s), bolt(s), friction fitting(s), etc.).

Referring now to FIGS. 2A-2D, example assembly steps (which examples areintended to be illustrative and not restrictive) associated with theartificial intervertebral disc of FIG. 1 are shown.

Referring now to FIG. 3, a cut-away view of the assembled artificialintervertebral disc of FIG. 1 is shown.

Referring now to FIG. 4, it is seen that Artificial Intervertebral Disc400 includes First Anchor Plate 402A and Second Anchor Plate 402B (eachAnchor Plate 402A, 402B may comprise, for example (which example isintended to be illustrative and not restrictive), any desiredbiologically acceptable metal). Of note, each Anchor Plate 402A, 402Bmay have an outer surface configured to be disposed adjacent arespective vertebral endplate (not shown). Further, Core 404 (e.g.,comprising an elastomer) is sandwiched between an inner surface ofAnchor Plate 402A and an inner surface of Anchor Plate 402B (in oneexample (which example is intended to be illustrative and notrestrictive), the inner surfaces of Anchor Plates 402A, 402B may beconvex and may be received in respective concavities in Core 404). Inaddition, First Chain Link 406A and Second Chain Link 406B (e.g., eachof which may comprise a polymer and/or a metallic material (e.g.,including a biologically acceptable metal)) are attached to AnchorPlates 402A, 402B. That is, First Chain Link 406A is attached at itsopen end to Anchor Plate 402B and second Chain Link 406B is attached atits open end to Anchor Plate 402A (when attached to the respectiveanchor plates the chain links interlock one another; in addition, theinterlocking chain links run from Anchor Plate 402A to Anchor Plate 402Bthrough a hole disposed in Core 404).

In one example (which example is intended to be illustrative and notrestrictive), First Chain Link 406A may be attached to Anchor Plate 402Bat depressions formed in an inner surface of Anchor Plate 402B andSecond Chain Link 406B may be attached to Anchor Plate 402A atdepressions formed in an inner surface of Anchor Plate 402A. In anotherexample (which example is intended to be illustrative and notrestrictive), First Chain Link 406A may be attached to Anchor Plate 402Bvia holes formed all the way through Anchor Plate 402B (i.e., holesextending from an inner surface of Anchor Plate 402B to an outer surfaceof Anchor Plate 402B) and Second Chain Link 406B may be attached toAnchor Plate 402A via holes formed all the way through Anchor Plate 402A(i.e., holes extending from an inner surface of Anchor Plate 402A to anouter surface of Anchor Plate 402A). In another example (which exampleis intended to be illustrative and not restrictive), First Chain Link406A and Second Chain Link 406B may be attached to Anchor Plates 402A,402B using any appropriate attachment mechanism (e.g., adhesive,welding, screw(s), bolt(s), friction fitting(s), etc.).

Referring now to FIGS. 5A-5D, example assembly steps (which examples areintended to be illustrative and not restrictive) associated with theartificial intervertebral disc of FIG. 4 are shown.

Referring now to FIG. 6, a cut-away view of the assembled artificialintervertebral disc of FIG. 4 is shown.

Referring now to FIGS. 7A-7F, example initial fixation mechanisms (whichexamples are intended to be illustrative and not restrictive) associatedwith artificial intervertebral discs according to the present inventionare shown.

More particularly, FIG. 7A shows Anchor Member 700 having threepyramidal type protrusions for gripping a vertebral endplate (notshown); FIG. 7B shows Anchor Member 702 having three conical typeprotrusions for gripping a vertebral endplate (not shown); FIG. 7C showsAnchor Member 704 having three spade or keel type protrusions forgripping a vertebral endplate (not shown); FIG. 7D shows Anchor Member706 having five pyramidal type protrusions for gripping a vertebralendplate (not shown); FIG. 7E shows Anchor Member 708 having fiveconical type protrusions for gripping a vertebral endplate (not shown);and FIG. 7F shows Anchor Member 710 having five spade or keel typeprotrusions for gripping a vertebral endplate (not shown). Of course,any desired number and/or placement of such initial fixation mechanismsmay be utilized.

Referring now to FIG. 8 (showing another embodiment of the presentinvention), it is seen that Artificial Intervertebral Disc 800 includesFirst Anchor Plate 802A and Second Anchor Plate 802B (each Anchor Plate802A, 802B may comprise, for example (which example is intended to beillustrative and not restrictive), any desired biologically acceptablemetal). Of note, each Anchor Plate 802A, 802B may have an outer surfaceconfigured to be disposed adjacent a respective vertebral endplate (notshown). Further, Column Filler 804 (e.g., comprising an elastomer) issandwiched between an inner surface of Anchor Plate 802A and an innersurface of Anchor Plate 802B (in one example (which example is intendedto be illustrative and not restrictive), the inner surfaces of AnchorPlates 802A, 802B may be concave for receiving therein Column Filler804). In addition, Column 806 (e.g., comprising DACRON) is held betweenFirst Inner Ring 808A and First Outer Ring 808B as well as betweenSecond Inner Ring 810A and Second Outer Ring 810B for attachment to eachof Anchor Plates 802A, 802B.

In one example (which example is intended to be illustrative and notrestrictive), Column 806 is held between First Inner Ring 808A and FirstOuter Ring 808B as well as between Second Inner Ring 810A and SecondOuter Ring 810B by crimping or rotary swaging.

In another example (which example is intended to be illustrative and notrestrictive), Column 806 is held between respective inner and outerrings for attachment to each of Anchor Plates 802A, 802B (such as, forexample, on outside vertical surfaces of Anchor Plates 802A, 802B) bywelding (e.g., laser welding) First Inner Ring 808A to Anchor Plate 802Aand Second Inner Ring 810A to Anchor Plate 802B.

Referring now to FIGS. 9-12 (showing another embodiment of the presentinvention), it is seen that Artificial Intervertebral Disc 900 includesFirst Anchor Plate 902A and Second Anchor Plate 902B (each Anchor Plate902A, 902B may comprise, for example (which example is intended to beillustrative and not restrictive), any desired biologically acceptablemetal). Of note, each Anchor Plate 902A, 902B may have an outer surfaceconfigured to be disposed adjacent a respective vertebral endplate (notshown). Further, Column Filler 904 (e.g., comprising an elastomer) isdisposed between an inner surface of Anchor Plate 902A and an innersurface of Anchor Plate 902B (in one example (which example is intendedto be illustrative and not restrictive), the inner surfaces of AnchorPlates 902A, 902B may be concave for receiving therein Column Filler904). In addition, Column 906 (e.g., comprising DACRON) is held betweenFirst Inner Ring 908A and First Outer Ring 908B as well as betweenSecond Inner Ring 910A and Second Outer Ring 910B for attachment to eachof Anchor Plates 902A, 902B.

Still referring to FIGS. 9-12, it is noted that each of First AnchorPlate 902A and Second Anchor Plate 902B may include Spikes 912 (e.g., toaid in initial fixation), Pockets 914 (e.g., for holding a porouscoating), and/or Attachment Features (e.g., for interface with one ormore holding/implantation instruments).

Referring now to FIGS. 13A-13F, additional details of the artificialintervertebral disc of FIG. 9 are shown. In this regard, FIG. 13A is atop view, FIG. 13B is a bottom view, FIG. 13C is a side view, FIG. 13Dis a side view, FIG. 13E is a side cut-away view (along section B-B ofFIG. 13A) and FIG. 13F is a detail view of portion “C” of FIG. 13E.

Referring now to FIGS. 14A-14D, additional details of a column and crimprings of the artificial intervertebral disc of FIG. 9 are shown In thisregard, FIG. 14A is an exploded view, FIG. 14B is a top view, FIG. 14Cis a side cut-away view (along section A-A of FIG. 14B) and FIG. 14D isa detail view of a portion of FIG. 14C.

Referring now to FIGS. 15A-15C, additional details of an inner crimpring of the artificial intervertebral disc of FIG. 9 are shown. In thisregard, FIG. 15A is a perspective view, FIG. 15B is a top view and FIG.15C is a side cut-away view (along section A-A of FIG. 15B).

Referring now to FIGS. 16A-16C, additional details of an outer crimpring of the artificial intervertebral disc of FIG. 9 are shown. In thisregard, FIG. 16A is a perspective view, FIG. 16B is a top view and FIG.16C is a side cut-away view (along section A-A of FIG. 16B).

Referring now to FIGS. 17A and 17B, additional details of a column ofthe artificial intervertebral disc of FIG. 9 are shown. In this regard,FIG. 17A is a top view and FIG. 17B is a side view.

Referring now to FIGS. 18A and 18B, additional details of a columnfiller of the artificial intervertebral disc of FIG. 9 are shown. Inthis regard, FIG. 17A is a perspective view and FIG. 17B is a side view.

Referring now to FIGS. 19A-191, additional details of an upper (i.e.,cephalad) anchor plate of the artificial intervertebral disc of FIG. 9are shown.

Referring now to FIGS. 20A-20I, additional details of a lower(i.e.,caudal) anchor plate of the artificial intervertebral disc of FIG. 9 areshown.

Referring now to FIG. 21, portions of an artificial intervertebral discaccording to another embodiment of the present invention are shown. Asseen in this FIG. 21, Column 2101 (e.g., comprising DACRON) is threadedbetween Upper Ring 2103A and Lower Ring 2103B. Although not shown inthis FIG. 21 for clarity, each of Upper Ring 2103A and Lower Ring 2103Bis attached (e.g., by welding) to a respective Upper Anchor Plate andLower Anchor Plate (each Upper Anchor Plate and Lower Anchor Plate maycomprise, for example (which example is intended to be illustrative andnot restrictive), any desired biologically acceptable metal). Further,each Upper Anchor Plate and Lower Anchor Plate may have an outer surfaceconfigured to be disposed adjacent a respective vertebral endplate (notshown). Moreover, although not shown in this FIG. 21 for clarity, ColumnFiller (e.g., comprising an elastomer) is disposed inside of Column 2101(in one example (which example is intended to be illustrative and notrestrictive), the inner surfaces of the Upper and Lower Anchor Platesmay be concave for receiving therein the Column Filler).

Referring now to FIGS. 22A-22N, diagrams of a surgical techniqueassociated with the present invention are shown.

More particularly, it is noted that one example of a surgical techniqueassociated with the present invention (which example is intended to beillustrative and not restrictive), may comprise the following steps:

-   -   Step 1, Access: Standard surgical approach to obtain adequate        visualization of the affected disc space (see FIG. 22A).    -   Step 2, Discectomy: Evacuate the affected disc space using        standard surgical procedures (see FIG. 22B).    -   Step 3.1, Distraction: Interbody distraction is achieved thru        the use of the Blade-Style Distractor. Insert the blade end of        the distractor into the interbody space, placing them as far        posterior as possible (this technique will help achieve parallel        spacing). Turn the ratcheting device until proper distraction        has been achieved (see FIG. 22C).    -   Step 3.2, Distraction: Once parallel distraction of the        interbody space has been achieved, (Blade Style Distractor may        remain in place) the Pin Style Distractor is used to allow for        access to the interbody space. Select desired pin styles. For        Pin Style 1, insert pins into the anterior aspect of adjacent        vertebral bodies. Once the pins are properly positioned, the        canulated arms of the distractor can be positioned into place.        The ratcheting device can then be actuated until proper        distraction has been achieved. Remove the Blade Style        Distractor. For Pin Style 2, place arms of the canulated        distractor in place on adjacent vertebral bodies. Drive the hex        top pins thru the canulated arms into the vertebral bodies. The        ratcheting device can then be actuated until proper distraction        has been achieved. Remove the Blade Style Distractor (see FIGS.        22D and 22E).    -   Step 4.1, Endplate Prep: End plate templates are provided to        check that the vertebral endplate will match the implant. Check        to make sure the template labeled “Top” is used for the inferior        end plate of the Cephalad vertebral body and the template        labeled “Bottom” is used for the superior end plate of the        Caudal vertebral body (see FIG. 22F and 22G).    -   Step 4.2, Endplate Prep: Shaping of the vertebral endplates, if        required, can be achieved thru broaching. The first Broach (see        FIG. 22H) is inserted into the disc space creating the MIL        clearance for proper implant fit. Followed by the second broach        (FIG. 22I), which removes the material from the posterior aspect        of the joint space.    -   Step 5, Implant Height Evaluation. Trial Sizing: Selection of        the proper implant is essential. Place the trials starting with        the smallest (e.g., 6 mm) in the disc space to determine the        proper implant size (height and footprint) (see FIG. 22J).    -   Step 6, Implant Insertion: Load the prosthetic device onto the        holder by aligning pins on holder (see FIG. 22K) with holes on        the implant (see FIG. 22L). Turn knob on holder to actuate the        jaws until a snug fit has been achieved. Place the device into        vertebral space using flouroscopy. Once satisfied with implant        placement, turn knob on holder to release the jaws and pull        instrument away from implant (see FIGS. 22M and 22N).

Referring now to FIGS. 23A and 23B, it is seen that ArtificialIntervertebral Disc 2300 includes First Anchor Plate 2302A and SecondAnchor Plate 2302B (each Anchor Plate 2302A, 2302B may comprise, forexample (which example is intended to be illustrative and notrestrictive), any desired biologically acceptable metal). Of note, eachAnchor Plate 2302A, 2302B may have an outer surface configured to bedisposed adjacent a respective vertebral endplate (not shown). Further,Core 2304 (e.g., comprising UHMPE) is sandwiched between an innersurface of Anchor Plate 2302A and an inner surface of Anchor Plate 2302B(in one example (which example is intended to be illustrative and notrestrictive), the inner surfaces of Anchor Plates 2302A, 2302B may beconcave for receiving therein Core 2304). In addition, Inner Column 2305(e.g., comprising an elastomer) is also sandwiched between the innersurface of Anchor Plate 2302A and the inner surface of Anchor Plate2302B. Moreover, Outer Column 2306 (e.g., comprising a PE (polyethelene)material, or polyester material (e.g., DACRON)) is held between FirstInner Ring 2308A and First Outer Ring 230813 as well as between SecondInner Ring 2310A and Second Outer Ring 2310B for attachment to each ofAnchor Plates 2302A, 2302B.

In one example (which example is intended to be illustrative and notrestrictive), Outer Column 2306 is held between First Inner Ring 2308Aand First Outer Ring 2308B as well as between Second Inner Ring 2310Aand Second Outer Ring 2310B by crimping or rotary swaging.

In another example (which example is intended to be illustrative and notrestrictive), Outer Column 2306 is held between respective inner andouter rings for attachment to each of Anchor Plates 2302A, 2302B (suchas on outside vertical surfaces of Anchor Plates 2302A, 2302B) by laserwelding First Inner Ring 2308A to Anchor Plate 2302A and Second InnerRing 2310A to Anchor Plate 2302B.

Referring now to FIGS. 24-27 (showing an embodiment of the presentinvention), it is seen that Artificial Intervertebral Disc 2400 includesFirst Anchor Plate 2402A and Second Anchor Plate 2402B (each AnchorPlate 2402A, 2402B may comprise, for example (which example is intendedto be illustrative and not restrictive), any desired biologicallyacceptable metal). Of note, each Anchor Plate 2402A, 2402B may have anouter surface configured to be disposed adjacent a respective vertebralendplate (not shown), Further, Column Filler 2404 (e.g., comprising anelastomer) is disposed between an inner surface of Anchor Plate 2402Aand an inner surface of Anchor Plate 2402B (in one example (whichexample is intended to be illustrative and not restrictive), the innersurfaces of Anchor Plates 2402A, 2402B may be concave for receivingtherein Column Filler 2404). In addition, Column 2406 (e.g., comprisinga polyester (e.g., DACRON)) is held between First Inner Ring 2408A andFirst Outer Ring 2408B as well as between Second Inner Ring 2410A andSecond Outer Ring 2410B for attachment to each of Anchor Plates 2402A,2402B.

Still referring to FIGS. 24-27, it is noted that each of First AnchorPlate 2402A and Second Anchor Plate 2402B may include Spikes 2412 (e.g.,to aid in initial fixation), Pockets 2414 (e.g., for holding a porouscoating), and/or Attachment Features (e.g., to interface with one ormore holding/implantation instruments).

Referring now to FIGS. 28-33, additional views of components of anartificial intervertebral disc according to another embodiment of thepresent invention are shown. Of note, the components shown in theseFIGS. 28-33 are similar to those of FIGS. 24-27, with the exception thatColumn 2806 has therein Radial Crimp 2806A (e.g., a crimp extendingaround a perimeter of Column 2806). In this regard, Radial Crimp 2806Amay provide flexibility which may: (a) help in assembling the AID; (b)help in implanting the AID; and/or (c) help in providing a desireddeflection behavior. Of further note, FIG. 32 shows Column 2806 in anuntrimmed state (thus, it is seen in this FIG. 32 has having a muchlonger aspect ratio than in the other Figs.).

Referring now to FIGS. 34-43 (showing an embodiment of the presentinvention), it is seen that Artificial Intervertebral Disc 3400 (shownin an exploded view in FIG. 34 and a cut-away view in FIG. 35) includesFirst Anchor Plate 3402A and Second Anchor Plate 3402B (each AnchorPlate 3402A, 3402B may comprise, for example (which example is intendedto be illustrative and not restrictive), any desired biologicallyacceptable metal). Of note, each Anchor Plate 3402A, 3402B may have anouter surface configured to be disposed adjacent a respective vertebralendplate (not shown). Further, Column Filler 3404 (e.g., comprising anelastomer) is disposed between an inner surface of Anchor Plate 3402Aand an inner surface of Anchor Plate 3402B (in one example (whichexample is intended to be illustrative and not restrictive), the innersurfaces of Anchor Plates 3402A, 3402B may be concave for receivingtherein Column Filler 3404). In addition, Column 3406 (e.g., comprisingan HTPET weave) is held between First Inner Ring 3408A and First OuterRing 3408B as well as between Second Inner Ring 3410A and Second OuterRing 3410B for attachment to each of Anchor Plates 3402A, 3402B.

Still referring to FIGS. 34-43, it is noted that each of First AnchorPlate 3402A and Second Anchor Plate 3402B may include Spikes 3412 (e.g.,to aid in initial fixation), pockets for holding a Porous Coating 3414,and/or Attachment Features (e.g., to interface with one or moreholding/implantation instruments).

As seen in these FIGS. 34-43, Column 3406 has therein Radial Crimp 3406A(e.g., a crimp extending around a perimeter of Column 3406). In thisregard, Radial Crimp 3406A may provide flexibility which may: (a) helpin assembling the AID; (b) help in implanting the AID; and/or (c) helpin providing a desired deflection behavior.

In another embodiment the AID assembly may be constructed of first andsecond anchor plates, each of which has a vertebrae contacting side, anda plurality of composite structures that are fixed to the first andsecond anchor plates. In one example (which example is intended to beillustrative and not restrictive) 2-8 composite structures may be fixedto the anchor plates.

In another embodiment the AID assembly may be provided with one or moreanchor plates that have one or more undercuts and/or one or more tabs tofacilitate the anchoring of the AID assembly to the vertebral bodies. Inone example (which example is intended to be illustrative and notrestrictive) the tabs may be provided with screw-holes into which bonescrews can be inserted to anchor the assembly to the vertebral bodies.In another example (which example is intended to be illustrative and notrestrictive) the screw holes and/or the tabs may be angled relative tothe vertebrae bodies (e.g., to pull all or part of the AID assemblydiagonally against the vertebrae).

In another embodiment the anchor plates may be assembled such that theanchor plates are non-parallel (e.g., in order to provide a profile thatsubstantially corresponds to the lordotic profile of the vertebralbodies/intervertebral space). In one example (which example is intendedto be illustrative and not restrictive), the non-parallel angle may beabout 5° to about 15°.

In another embodiment a final AID assembly may be comprised of multipleassemblies (e.g., matching left and right assemblies), each assemblyhaving first and second anchor plates and at least one compositestructure that is fixed to the anchor plates. In one example (whichexample is intended to be illustrative and not restrictive) the left andright assemblies may be sized and dimensioned to reside adjacent to eachother when positioned in the space between vertebral bodies.

In another embodiment (e.g., related to a modular design) the column(s)of the composite structure(s) may be terminated to intermediateend-pieces, which are then affixed to the anchor plates by one or moreof a variety of means, thus allowing for interchangeable heights andstiffnesses to provide a custom device for a patient's specific needs.Such customization may be provided, for example (which example isintended to be illustrative and not restrictive), via use of screw(s),threaded mechanism(s), and/or various sized insert(s) and/or ring(s).

Of note, making a portion of the column of the composite structurerelatively hard (and/or connecting the column of the composite structureto a relatively hard flange or other device) may aid in attaching thecolumn of the composite structure to the anchor plates.

Of further note, it is contemplated that each AID assembly of thepresent invention may be inserted using any desired surgical approach.For example (which example is intended to be illustrative and notrestrictive), a posterior approach may be utilized. In another example(which example is intended to be illustrative and not restrictive), aposterior, lateral approach may be utilized. In another example (whichexample is intended to be illustrative and not restrictive), an anteriorapproach may be utilized.

In another embodiment, the AID may come in variety of ‘widths’. Forexample (which example is intended to be illustrative and notrestrictive), one AID assembly may have a “narrow” width, another AIDassembly may have a “regular” width and a third AID assembly may have a“wide” width.

In another embodiment, the AID may come in variety of lengths. Forexample (which example is intended to be illustrative and notrestrictive), one AID assembly may have a “short” length, another AIDassembly may have a “regular” length and a third AID assembly may have a“tall” length.

Of note, such multiple “widths” and/or multiple “lengths” could providethe potential for the greatest amount of surface contact between thedevice and the vertebral endplate, thus lowering the contact stressesand reducing the potential for subsidence (gradual “sinking” of thedevice into the adjoining vertebral bodies).

Additionally, it is noted that during the surgical preparation of thevertebral endplate, a surgeon may scrape/score the bony surface in orderto promote bone growth with the intention of securing ultimate fixationbetween vertebra and implant. If the scraped/scored surface is largerthan the implanted device, there is a greater likelihood of bone growingup around the perimeter of the device, eventually causing bone bridging,fusing the spinal segment. A device with a surface that better matchesthe prepared endplate in terms of area coverage may help discourage thisbehavior.

In another embodiment the column may be an essentially solid chord orpiece of material.

In another embodiment the column may be an essentially solid combinationof materials.

In another embodiment a column could be made to have greater wallthickness on one side or end as opposed to another side or end. Forexample (which example is intended to be illustrative and notrestrictive), the walls of the anterior side may be made thicker thanthe walls of the posterior side.

In another embodiment the AID assembly may be customized to provide anydesired articulation, kinematic behavior, dynamic behavior and/or staticproperties for any given application (e.g., implantation site) and/orpatient (e.g., gender, age, height, weight, activity level). For example(which examples are intended to be illustrative and not restrictive):

-   -   1. The articulation, kinematic behavior, dynamic behavior and/or        static properties exhibited by the column(s) may be modified by        varying the density and/or composition of the material.    -   2. The articulation, kinematic behavior, dynamic behavior and/or        static properties exhibited by the column filler may be modified        by varying the density and/or composition of the material.    -   3. The articulation, kinematic behavior, dynamic behavior and/or        static properties exhibited by the AID assembly may be modified        by varying (for individual components (e.g., column, column        filler, intermediate elements, anchor plates)):        -   a) column height;        -   b) column width (e.g., diameter);        -   c) column cross-section (shape and/or area);        -   d) column wall thickness;        -   e) column stiffness modulus;        -   f) filler height;        -   g) filler width (e.g., diameter);        -   h) filler cross-section (shape and/or area);        -   i) filler stiffness modulus;        -   j) anchor plate material;        -   k) anchor plate shape;        -   1) anchor plate stiffness modulus;        -   m) intermediate element material        -   n) shape (e.g., curvature) of an interface between the            filler and an anchor plate or intermediate element    -   4. The articulation, kinematic behavior, dynamic behavior and/or        static properties exhibited one or more composite structures in        a multiple composite structure AID assembly may be modified by        varying one or more parameters discussed at paragraph 3, above,        to render one or more of the composite structures stiffer than        one or more of the other composite structures in order to add        stiffness locally and to aid in mimicry of in vivo        non-homogeneous stiffness topography (e.g., the in vivo        topography relating to the area of relatively higher stiffness        in the posterior region of the vertebral body versus the        relatively lower stiffness in the anterior region of the        vertebral body).    -   5. In the context of a multiple composite structure AID        assembly, one or more of the composite structures may be        positioned appropriately between the anchor plates as follows:        -   a) one or more composite structures may be placed an            increased distance from the center of the implant (e.g., to            aid in increasing torsional stiffness of the implant);        -   b) lateral positioning of one or more composite structures            may be used (e.g., to aid in controlling lateral bending            stiffness of the implant); and/or        -   c) fore/aft positioning of one or more composite structures            may be used (e.g., to aid in controlling flexion/extension            stiffness of the implant).    -   6. In the context of a multiple composite structure AID        assembly, any desired number of composite structures may be        utilized.    -   7. In the context of a multiple hole composite structure, the        articulation, kinematic behavior, dynamic behavior and/or static        properties exhibited may be controlled in a similar manner as        discussed at paragraphs 4-6, above, with regard to the multiple        composite structure AID (e.g., the spacing between the holes may        be varied, the size/cross-sectional area/cross-sectional shape        of the holes may be varied, the position of the various holes        may be varied, the number of holes may be varied etc.).

In another example (which example is intended to be illustrative and notrestrictive), the composite structure may be configured such that thecomposite structure has associated therewith, in at least one axis, aload versus deflection behavior substantially similar to that of asubstantially healthy human intervertebral disc.

In another example (which example is intended to be illustrative and notrestrictive), the load versus deflection behavior may be selected fromthe group including (but not limited to): (a) dynamic behavior, whichdynamic behavior is a function of a time rate application of load; (b)kinematic behavior; and (c) static behavior.

In another example (which example is intended to be illustrative and notrestrictive), the load versus deflection behavior may include anon-linear relationship between an amount of force required to compressthe composite structure and a deflection of the composite structure.

In another example (which example is intended to be illustrative and notrestrictive), a stiffness of the composite structure may increase as thecomposite structure is compressed.

In another example (which example is intended to be illustrative and notrestrictive), the elastomer may be selected from the group including(but not limited to): (a) a silicone; (b) a urethane; and (c) athermoplastic elastomer

In another example (which example is intended to be illustrative and notrestrictive), the column may be impregnated with a material that aids inpreventing at least one of (but not limited to): (a) biological ingrowthinto the column; and (b) biological attachment to the column.

In another example (which example is intended to be illustrative and notrestrictive), the column may be coated with a material that aids inpreventing at least one of (but not limited to): (a) biological ingrowthinto the column; and (b) biological attachment to the column.

In another example (which example is intended to be illustrative and notrestrictive), the artificial intervertebral disc may be configured to beimplanted by at least one method selected from the group including (butnot limited to): (a) posterior implantation; and (b) anteriorimplantation.

In another embodiment the column and/or the column filler may contain acompression element (e.g., a spring (e.g., constructed of abiocompatible material, such as titanium)).

Of note, the materials used in constructing the AID assembly may bestrong, durable and biocompatible. For example (which example isintended to be illustrative and not restrictive), the anchor plates maybe constructed of titanium 6AL4V ELI (extra low interstitial), atitanium alloy containing 6% aluminum and 4% vanadium. Any elastomericor non-elastomeric materials utilized in the assembly may bebiocompatible. One of ordinary skill in the art would readily appreciatethe other materials that could be used to construct implants accordingto the present invention.

As mentioned above, the column(s) may be coated (e.g., to help prohibitthe growth of tissue and/or bone on the column(s). In one example (whichexample is intended to be illustrative and not restrictive), the coatingmay be silicone, urethane, any desired biocompatible elastomer layerand/or any combination thereof.

In another embodiment the column(s) may be impregnated with the filler(e.g., the elastomer).

In another embodiment the device may resist shear translation andflexion of the spine and may produce shear at one or more adjacentjoints (e.g., a superior adjacent joint).

In another embodiment flexion/extension may produce shear translationand rotation of a superior vertebral body.

In another embodiment one or more of the anchor member surfaces may beshaped to substantially match adjacent vertebral endplate surfaces toallow for minimal “carpentry” (or bone removal/shaping) during surgeryto achieve good contact area (e.g. in cervical spine, the cephalad(towards the head) surface of the implant may be convex in the A-P(anterior-posterior) direction to match the A-P concavity in thevertebral endplate on the caudad (towards the feet) end of the vertebralbody cephalad to the disc space and the caudad surface of the implantmay be convex laterally to match the lateral concavity in the vertebralendplate on the cephalad end of the vertebral body caudal to the discspace).

In another embodiment one or more pieces of the AID may be sterilizedseparately, or a final AID unit may be sterilized as a unit. In onespecific example (which example is intended to be illustrative and notrestrictive), a final AID unit may be placed in a pouch and thensterilized (through the pouch).

-   -   -   Various structural features of the invention, and methods            for installing an AID assembly, and for stabilizing the AID            assembly, have been described. In this regard, it is            believed that when the AID assembly of the present invention            is inserted between vertebral bodies and subjected to            customary loads, the AID assembly may perform similar to the            way in which a healthy intervertebral disc would perform. Of            note, the implants of the present invention may provide one            or more of the following attributes when inserted in the            body (e.g., between vertebrae):

    -   Essentially the same articulation as a healthy intervertebral        disc (e.g., intervertebral lumbar disc, intervertebral cervical        disc, intervertebral thoracic disc) may be realized;

    -   Essentially the same kinematic behavior as a healthy        intervertebral disc (e.g., intervertebral lumbar disc,        intervertebral cervical disc, intervertebral thoracic disc) may        be realized;

    -   Essentially the same dynamic behavior as a healthy        intervertebral disc (e.g., intervertebral lumbar disc,        intervertebral cervical disc, intervertebral thoracic disc) may        be realized;

    -   The static properties of the implant and a healthy        intervertebral disc (e.g., intervertebral lumbar disc,        intervertebral cervical disc, intervertebral thoracic disc) may        be substantially identical;

    -   The implant may be biocompatible;

    -   The device may be implanted by posterior and/or anterior        approaches;

    -   The device may install in a relatively short period of time        (e.g., around 90 minutes);

    -   The device may exhibit positive results in fatigue tests (e.g.,        the device may be usable after 10×10⁶ cycles); The device may        survive static loading, shear loading and testing to induce        expulsion;

    -   The device may fixate relatively rapidly to vertebral bodies;

    -   The device may minimize contact stress with vertebral bodies at        the device interface; and

    -   The device may be auto-clavable.

In other embodiments the AID assembly may include one or more of thefollowing features:

-   -   The device may have lordosis (lordotic angle) built in (in one        example the lordotic angle may place the composite structure        substantially coincident with the axis of the functional spinal        unit (“FSU”)    -   The anchor plate(s) may have surface treatment(s) to encourage        osseointegration (bony ingrowth) to establish ultimate fixation        to vertebral endplates. Such surface treatments may include (but        not be limited to): electrochemical etch; plasma-sprayed Ti;        sintered metallic beads or shards;        bioactive/osseoinductive/osseoconductive ceramic coating (e.g.,        hydroxyapatite (HA))    -   The device may employ no screws, a single screw or multiple        screws for fixation    -   The device may include features to establish immediate fixation        to vertebral endplates. Such features may include (but not be        limited to): screw(s); keel(s); serration(s) (e.g.,        backward-facing serrations or angled bosses to ‘bite’ into        place); sharp protrusion(s); finger(s)/protrusion(s) that can be        deployed once device is in place    -   The device may dampen strain energy via compliant composite        structure(s)    -   The columns may be reinforced. Such reinforcement may include        (but not be limited to): exterior reinforcement; interior        reinforcement; circumferential rib(s)/band(s); spiral        ribbing/banding; rib(s)/band(s) of nitinol, metal;        rib(s)/band(s) disconnected from column; rib(s)/band(s)        connected to column; fusion weld; as part of extrusion process    -   A connection between a column and an anchor plate may include a        frictional component, for example, due to compressive force        capturing column/flange to plate (friction may be enhanced by        roughened surface geometry (e.g., on mating anchor plate        surface))    -   A capturing component may be welded to an anchor plate    -   Holes in an anchor plate may enhance ability of sterilization        (e.g., with EtO gas)    -   The column may be designed such that when the AID assembly is in        neutral condition (e.g., not flexed or twisted) the column        (e.g., the DACRON) is somewhere in the middle of its elongation        ratio (not fully compressed or elongated).    -   The column surrounding the column filler may constrain the        radial bulge of the column filler during compression, causing        the load-deflection response of the composite structure to be        non-linear, like a healthy disc    -   A bi-concave core may ride on convex dome surfaces such that the        core follows the motion of the ‘leading’ anchor plate, promoting        motion that mimics the shear displacement in an intact disc        during bending    -   The AID assembly may have multiple height options to        appropriately match the height of disc being replaced and        allowing for appropriate distraction to the segment during and        after surgery to decompress anatomy, e.g. foraminal nerves        (addressing the pathology)    -   The AID assembly may have multiple sizes (e.g., in the        anterior-posterior (A-P) dimension), allowing for proper        placement of the composite structure coincident with the axis of        the FSU

In another embodiment the column of the composite structure may beaffixed to the anchor plates to form a structural unit (this is, thecolumn forms a structural “bridging link” between the anchor plates).

In another embodiment the AID assembly is not pre-stressed. Since theAID assembly of this embodiment is not pre-stressed, the column filler(e.g., elastomer) will not exhibit any significant amount of “creep”. Inaddition, the AID assembly of this embodiment will, at times, be underessentially no stress (e.g., when the patient using the AID assembly islying down). Of note, this is similar behavior to a natural disc.

Of note, when a column is utilized without a column filler (e.g., in theform of an essentially homogeneous structure), such a column may beintegrated into the AID assembly (e.g., in terms of attachment to theanchor plates, patient customization) in essentially the same manner asa composite structure discussed herein.

In another example (which example is intended to be illustrative and notrestrictive), the surgeon may (during the surgical procedure) make therequisite incisions or access the site where the unhealthy or damageddisc is to be removed. After removal of the unhealthy or damaged disc orthe unhealthy or damaged portion(s) of the disc, the surgeon may cutgrooves in the endplates of the vertebral bodies that were adjacent tothe removed disc. The grooves that are cut may be sized and shaped tocorrespond to an interface on an elevated portion of the anchorplate(s). Of note, the surgical procedure may also involve removinghealthy portion(s) of the patient's disc(s) to the extent required forimplantation of the AID assembly.

In one embodiment the compressibility of the implant of the presentinvention may prove helpful during the implanting procedure. Forexample, (which example is intended to be illustrative and notrestrictive), as the implant is being inserted between the vertebrae,the implant may be compressed to smaller proportions than itsuncompressed height. The surgeon can then, prior to releasing theimplant from its compressed height, adjust its position to insure thatthe elevated interface on the anchor plates and the grooves cut into thevertebral bodies are aligned with each other. After the surgeon hasensured this is the case, the implant may be released from itscompressed state (e.g., so that the elevated interface enters thegrooves)

Alternatively, the grooves may be cut in the vertebral body with amatching undercut, such that the anchor plates may be inserted (e.g.,from the side, front or back) in a dovetail configuration. Thisembodiment may allow for positive initial tensile attachment between theanchor plates and the endplates, without having to wait for bonyingrowth.

While a number of embodiments of the present invention have beendescribed, it is understood that these embodiments are illustrativeonly, and not restrictive, and that many modifications may becomeapparent to those of ordinary skill in the art. For example, one or morecomponents may be constructed of Ti, cobalt chromium, surgical steeland/or any combination thereof. Further, customization may be carriedout using multiple, interchangeable components (e.g., interchangeablecomposite structures). Further still, the customization may be carriedout using a family of standard parts. Further still, customization ofthe AID assembly may be done at the place of manufacture (e.g., by atechnician at the factory) and/or at the place of implantation (e.g., bya surgeon at the hospital). Further still, the vertebra contacting sideof the anchor members (i.e., the side of the anchor members facing the“upper” and “lower” faces of the vertebrae) may include gripping, tissueingrowth promoting and/or bone ingrowth promoting elements, such as, forexample (which examples are intended to be illustrative and notrestrictive), grooves, teeth, protrusions, depressions or anycombination thereof. Further still, mounting tabs associated with theanchor members (which mounting tabs may contact the vertebrae on thegenerally vertical “outer” faces thereof) may interface with thevertebrae along a planar interface, a curved interface, or a combinationthereof. Further still, the mounting tabs may include gripping, tissueingrowth promoting and/or bone ingrowth promoting elements such asdescribed above. Further still, the column filler (e.g., elastomer)within the column may be of sufficient hardness as to form a distinct“core” within the column (such that the core fills essentially theentire space within the column or the core fills less than the entirespace within the column (e.g., having one or more voids above the core,below the core and/or around the core between the core and the column)).Further still, the column filler (e.g., elastomer) within the column maybe of insufficient hardness as to form a distinct “core” within thecolumn but may instead fill the column in a more or less “fluid” manner(such that the column filler fills essentially the entire space withinthe column or the column filler fills less than the entire space withinthe column (e.g., having one or more voids above the column filler,below the column filler and/or around the column filler between the coreand the column). Further still, the column filler (e.g., elastomer) maybe extruded/injected onto the column(s). Further still, the columnfiller (e.g., elastomer) may protrude out from the top, bottom and/orside(s) of the column. Further still, the protruding column filler(e.g., elastomer) may be used to aid in attachment of the compositestructure to the anchor plate (e.g., the protruding elastomer may beattached directly or indirectly (via an intermediate element) to ananchor plate using any desired attachment mechanism). Further still, thecolumn may comprise any desired fiber and/or fabric. Further still, theattachment of the column(s) and/or composite structure(s) to the anchorplates may be carried out using a press fit, a rotary swage, welding(e.g., spot or continuous), a number of discrete interference dings, aforced interference fit, a threaded fit, a punch mechanism at a seambetween parts and/or any other desired method (as well, of course, asany combination thereof). Further still, the device may be shaped asdesired, such as having a circular shape, an oval shape or a kidneyshape, for example (this could be effected by providing a desired shapeto any of the components (e.g., the anchor plates and/or the column(s)and/or the composite structure(s))). Further still, the compositestructure(s) may essentially fill the space between the anchor plates orthere may be empty space between the composite structure(s). Furtherstill, the column filler, the material used to coat the column(s) and/orthe material impregnated into the column(s) may be any desiredcompressible, elastic compressible, extrudable and/or flowable material(or combination thereof). Further still, the load/deflection curvesassociated with the present invention may result from underlying datahaving applied thereto any desired type of curve fitting (e.g.,polynomial curve fitting to the second or third power). Further still,all dimensions, engineering notes, specifications, etc. identified inthe Figs. are intended to be examples and not be restrictive. Furtherstill, any desired number of crimps may fully and/or partially encirclethe perimeter of the column. Further still, any steps may be carried outin any desired order (and certain steps may be omitted and/or othersteps added).

1-27. (canceled)
 28. A method of constructing an artificial intervertebral disc, comprising: providing a column comprising a first polymeric material; providing a column filler comprising a second polymeric material; providing a first crimped-ring set comprising a first inner ring and a first outer ring, the first crimped-ring set being disposed adjacent a first end of the column, and at least a portion of the column being held between the first inner ring and the first outer ring; providing a second crimped-ring set comprising a second inner ring and a second outer ring, the second crimped-ring set being disposed adjacent a second end of the column, and at least a portion of the column being held between the second inner ring and the second outer ring; providing a first anchor member; and providing a second anchor member, wherein at least one of the first inner ring and the first outer ring of the first crimped-ring set provides a mechanism to attach the column to the first anchor member, and at least one of the second inner ring and the second outer ring of the second crimped-ring set provides a mechanism to attach the column to the second anchor member.
 29. The method of claim 28, wherein the steps are carried out in the order recited. 